1. Field of the Invention
The present invention relates to a magneto generator which generates electricity under the electromagnetic induction action of magnets and magneto coils in accordance with the rotation of a flywheel.
2. Description of the Related Art
In a known alternator, in order to suppress the generation of heat due to eddy currents, magneto coils are arranged on a laminated core which is formed by laminating a plurality of magnetic thin sheet steel plates one over another, and a plurality of permanent magnets, which are fixedly secured to an inner surface of an outer peripheral edge of a flywheel in a circumferentially spaced apart relation with respect to one another, are disposed on the outer peripheral sides of the magneto coils. A pair of hollow disk-shaped end plates comprising magnetic steel plates of high strength each having a thickness larger than that of each thin sheet steel plate are disposed on the opposite side surfaces, respectively, of the laminated core. The outer peripheral portion of each end plate is bent toward the magneto coil side so as to hold the magneto coils in place and to induce magnetic fluxes in the windings of conductive wires of the laminated core (for example, see a first patent document: Japanese patent laid-open No. 2001-275283).
In the alternator as constructed above, particularly in case of a magneto generator, the following problems arise. That is, heat generation due to hysteresis losses and eddy current losses are caused by alternating fields generated by the permanent magnets when the flywheel is rotating. In particular, at the L-shaped bent portion of each end plate, there are induced magnetic fluxes, and hence the density of magnetic fluxes is high, resulting in large hysteresis losses. On the other hand, heat generation due to eddy current losses becomes large because of the large thickness of each end plate. As a result, the temperature of the laminated core rises, in accordance with which the temperature of each magneto coil also increases, and hence the resistance value of each magneto coil increases, too. Thus, the temperature of each magneto coil rises due to the copper or ohmic loss thereof which is in proportion to the resistance value of each magneto coil, resulting in reduction in the electrical efficiency.
In addition, copper wires used for the magneto coils are each covered with an insulation film of a high polymer material. This poses another problem in that the service life and reliability of the magneto coils are reduced when the temperature of each magneto coil rises, with the high temperature state of the magneto coils being continued for a long time.